This invention relates to certain N-substituted oxobenzothiazolines which are useful in a method of regulating plant growth, especially leguminous plant growth, as well as to plant growth regulant compositions. Compounds which are useful in regulating the growth and development of crop plants have become increasingly important as the rapidly increasing world population continues to greatly increase the pressure on available world food supplies. An increase in food production through increased land utilization is not a viable solution to this problem because, although more land can be put into production than is now being cultivated, much of that land is marginal and may, in order to be productive, require substantial inputs of water and fossil fuel energy, which are themselves diminishing resources. As a result, the use of chemicals to produce yield increases through the physiological manipulation of the crop plant offers an important means of increasing crop yield.